Shock-absorber and antirecoil device.



Patented Nov. 17, 1914.

J. C. SHERMAN.

SHOCK ABSORBER AND ANTIREGOIL DEVICE.

APPLICATION FILED AUG.10. 1910.

J'DHN C. SHERMAN, OF BROOKLINE, MASSACHUSETTS.

SHOCK-ABSORBER AND ANTIRECOIL DEVICE.

Specification of Letters Patent.

Patented Nov: 17, 11914 Application filed August 1.0, 1910. Serial No. 576,582.

To all whom it may concern:

Be it known that 1, JOHN C. SHERMAN, a citizen of the United States, residing at Brookline, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Shock- Absorber and Antirecoil Devices, of which the following is a specification.

This invention relates to shock absorbers, so called; that is, devices which are applied to bodies mounted upon springs for the purpose of protecting the spring or springs against sudden blows by resisting sudden movement of the spring mounted body with relation to the support for the springs. Devices of this character are applied to motor vehicles in such manner as to oppose sudden movement of the body with relation to the running gear, to the end that the vertical movements of the running ear may be substantially eliminated instea of being transmitted to the body or upper structure of the vehicle.

There are various types of shock absorbers now in use, one of which is the pneumatic type. It is to this specific type that the present invention relates. The mechanical devices necessary for utilizing pneumatic action are a chamber, which is usually cylindric, and a piston cotiperating therewith. The chamber may be entirely closed, or may be provided with vents, or arranged to permit relatively slow leakage of the compressed air or gas. If the chamber is provided with vents, the energy expended in compressing the air becomes lost as fast as the air escapes through the vents, consequently a pneumatic shock absorber provided with vents through which the air may escape while bein compres loses the compressing energy efore the piston may return to its normal position. If the device is not provided with any means of escape for the compressed air the device is nothing more than a cushion of extremely resilient character and is not ada ted to eliminate relative movement but is d to increase recoil movement.

The present invention comprises apiston and compression chamber which is closed automatically during compression, and means for transferrin the compressed air or gas to the opposite side of the piston after the completion of the compressing stroke, so that the air which previously opposed movement of the piston in one direction and which contains a substantial proportion of com ressing energy serves to op ose retrogra e movement of the piston. e air being compressed before it is transferred to the opposite side of the piston has a rela tively great initial pressure to oppose the return stroke, but this pressure is further increased by the piston during its return stroke. The device therefore possesses the advantage of having a closed chamber to oppose with relatively great efiiciency the first stroke of the iston and the additional advantage of app ying the energy already stored in a way which 0 oses reverse movement of the piston. f e same air which opposes movement of the piston in one direction therefore serves to oppose movement in the opposite direction.

The device embodying the resent invention is desi ned for a specia purpose. A motor vehic le traveling over a highway in good condition does not require any device of this kind. It is desirable that the body of a motor vehicle be relatively free to play up and down upon its springs under usual conditions. It is only when the vehicle strikes a comparatively large obstacle that it is advisable to oppose free movement of the body of the vehicle. The present invention is designed to satisfy the conditions named. In fact, the present invention does more than that. Under ordinary conditions such as prevail on a highway in good condition, the device shown b the present invention serves as an additlonal cushion for supplementing the resilience of the vehicle springs, and it does not operate so as to eliminate relative movement of the vehicle body unless the vehicle springs are co npressed to an abnormal degree. The device therefore serves two purposes: First, when the vehicle is running over a smooth road the device acts as. an additional cushion, thus sharing with the springs in supporting the load; second, when the vehicle strikes an unusually large obstacle the device not only protects the springs by preventing sudden and excessive compression of the same, but it prevents subsequent excessive distention of the springs because for that purpose it utilizes the force which it received when opposing compression. l

Of the accompanying drawings which illustrate one form in which the present invention may be embodied: Figure 1 represents a small portion of a motor vehicle in side elevation. Fig. 2 represents a central vertical section of the device in its normal or median position. Fig. 3 represents a simi- .lar section of the device in the position which it occupies at the end of a spring cornpressing stroke. Fig. t represents a similar section of the device showing the piston at the other limit of its movement. Fig. 5 represents on a larger scale a check valve carried by the piston.

T hesarne reference characters indicate the same parts wherever they occur.

in l ig. l a portion of the frame of a vehicle body is indicated at 10. Anaxle is shown in cross section at Ill. The upper and lower halves of an elliptic vehicle spring are indicated l2, 12, the lower hall heing as mounted upon the axle l1 and. the other hall being connected with the body frame 10 so as to support the same. it should not he presumed that the device hereina'lter descrihed is applicable only to this 35 type of spring, hecause, in fact, the spring is not in anyway a controlling factor, and any other type would be equally assisted by the device the present invention. The casing of shoal: absorloer is indicated at it. This casing incloses a bushing ill which divided the interior or the casing into two chambers indicated respectively at ll l8. chamber l? is relatively large, and the chamber l8 is relatively small. The chanaher l is occupied. by a piston 39 termed at one end oi a plunger 20 which is titted to slide in the chamber 18. The plun- 26 constitutes a piston in its relation to the chamber 18. outer end ol'the cham- JU bcr ll is closed by an end wall oil the casing, and the outer end of chamber is closed by end 521. piston rod 22 is a' ed to plunger 20 and has a hearing he d all.

in the .t or o venienee in attaching the device.

wall of the casing if is provided an and the outer end oi piston rod provided with eye 24%. shown by v the ear and the eye a so pivotally c r d as indicated at and 2h to the o fee-l2 respectively of the vehicle a is not necessary that the 3. rod be attach ed duit is only a bore 2 of its movement.

tor either the piston 19 or plunger 2 inset they he attached respectively to any parts which are fixed respectively with relation to the frame of the running gear and the vehicle body.

The lunger 20 is provided with a central extending from the outer lace oil the piston 19 to a transverse port 28 near the piston end oil the plunger. The bushing 16 is provided with a bypass .29, of which both ends open into the chamber 18, as indicated at 30 and 31. The openings 80 and 31 are arranged to register with the port 28 when the plunger 20 is near either limit lit will be further observed that the opening 30 is slightly flared, the purpose oi which is hereinafter explained.

The central passage 27 in the plunger is provided with a check valve "for the purpose of preventing a downward flow of air and for permitting an upward flow. ll. hall checlr valve is illustrated for this purpose, and is illustrated on a relatively large scale by Fig. 5. A dislr or washer 32 having a central hole 33 constitutes the valve seat for a ball valve 84, the ball being arranged upon the upper side of the disk as to be adapted to be normally seated by gravity. A perforated disk 35 is fixed in the passage 27 above the hall to prevent the ball from closing the passage and obstructing the upward flow of air. The last remaining teature of construction of the plunger is a secondary toy-pass 86, of which one end is arranged to register with the opening 30 and of which the other end remains in the chamher 17.

The casing 15 is provided with one or more-holes 3T, 88 and 39 to serve as vents under certain conditions hcreii'iaiter speci There is no necessity for packing rings 6*, for very slight leakage for both the chambers 1i" and 18 is desirable. For this reason it is not necessary to finish the pistons and the walls of the chambers with extreme accuracy. A slight leakage between. the preton rod 22 and its hearing in the hear it is also preterable, although is not necessary to provide any more leaiiagc than would he the result of fitting the piston rod 1 to slide easily in its hearing.

The normal or position the device is shown to l and 2. is position which i would occupy vehieleie cariy ag' the load for v.1 j intended. it will he to Fig. 2 hole 3%) and that the charnher .l'? is chamber. The oniy lealrage under these conditions would be hctween the piston it the casing, and a slight its the chamber 18 and through the bearing in the head 21. The aggregate leakage at these points is negligible, but at the same time is sufficient to permit the pressure in either of the chambers to increase or decrease to atmospheric pressure within the space of a few seconds under ordinary conditions.

To describe the operation of the device when the vehicle strikes an unusually large obstacle, such as a railroad crossing, for example, it may be assumed that-the plunger is in the position shown in Fig. 2 immediately prior to striking the obstacle. The efi'ect of striking the obstacle is to force the axle upwardly and to compress the vehicle spring. t the same time, the lower end of the easing 15 rises to meet the piston 19. In this way the air between the piston 19 and the lower end of the casing is compressed without any appreciable leakage. At the same time, the port 28 is closed by the bushing 16 until the vehicle spring has been so far compressed as to cause the port 28 and opening 30 to register one with the other. The opening 30 is lo cated so as not to register with the port 28 for relatively slight compressions of the vehicle springs but only for maximum or nearly maximum compressions. Therefore, it may be assumed that the port 28 and opening 30 register with each other at or near the limit of a maximum relative movement of the plunger. This position is shown by Fig. 3. The flaring of the opening 30 increases the range of registration with the port 28, and as soon as the port 28 registers with any part of the opening 30 the air which is compressed in the lower part of the chamber 17 may escape through the passage 27 into the by-pass 29 and thence into the chamber 18. When the compressed air in the lower part of the chamber 17 has so far escaped into the chamber 18 as to be equal in pressure in both chambers, the ball check valve 34 automatically closes and prevents a return of the air. The energy stored in the vehicle springs now expends itself in projecting the vehicle body upwardly, thus moving the plunger in the opposite direction; The movement of the plunger 20 is now opposed by the air already under pressure which has been transferred to the small chamber 18. The return stroke of the plunger is therefore opposed to a corresponding degree, because the only escape for the air from the chamber 18 is through the bearing in the head 21 and between the plunger and the bushing 16. The leakage at these points is negligible when the plunger moves rapidly, and the upper end of the plunger is therefore opposed by a cushion of compressed air in a substantially closed chamber. When the plunger has risen so far as to cause the upper end of the by-pass 36 to register with the opening 30, as shown by Fig. 4, the air which is thus further compressed by the upward stroke of the plunger escapes to the atmosphere through the secondary by-pass 36 and vent 37'.

When the piston 19 is in the position shown by Fig. 4, the lower part of the chamber 17 is opened to the atmosphere by the holes 38 and 39, so that when the piston returns to its normal position the'pressure in the closed portion of the chamber 17 will be approximately the same as that of the atmosphere.

Having thus explained the nature of my said invention and described a way of constructing and using the same, although without attempting to set forth all of the forms in which it may be made or all of the modes of its use, what I claim is:

1. A shock eliminator comprising two relatively movable air-compressing elements forming two compressing chambers and having cooperative conduits the mouths of which are arranged to move to and from register with each other as said elements move relatively to compress, two of said conduits being arranged to transfer a compressed charge from one of said chambers to the other when said elements are at or near one extreme of relative movement, and two of said conduits being arranged to vent said other chamber when said elements are at or near the other extreme of relative movement, said chambers being otherwise closed.

2. A. shock eliminator comprising two members, one .movable back and forth within the other, the outer member having closed ends of relatively large and small internal diameter, and the inner member having ends of corresponding size fitted to compress a charge in either end of the outer member, means whereby said members may be moved with relation to each other, and conduits formed respectively in the inner and outer members and arranged to be closed when said members are between the limits of their relative movement,and to be opened when said members are at the limits of such movement, whereby acharge may be confined and compressed in the larger end of the outer member, then conducted by the said conduits to the smaller end of the outer member, and then again confined and compressed in said smaller end by reverse relative movement of said members.

3. A shock eliminator comprising two members, one movable back and forth within the other, the outer member having closed ends and the inner member fitting closely within the outer member and adapted to compress a charge in either end thereof, means whereby said members may be moved with relation to each other, and conduits tormett in seioi members endl arranged to he closed when smd members are between their limits of relative movement, and to register with each other when said members are at their limits of movement, whereby a charge may be compressed in one end of the outer member by movement in one di reotion, then conueted to the opposite end, then compressed by reverse movement, then 10 conducted a second time through the inner w mtimeet member to he discharged, seidt outer me'mhet having an outlet through which the charge may be disehargect. in testimony whereof I have ettixedl my signature, in presence of two Witnesses.

JOHN C. @HERMAN.

Witnesses:

W. P. AEELL, P. W. PEZZETIL 

